The present invention, in some embodiments thereof, relates to imaging and, more particularly, but not exclusively, to devices and methods of generating three dimensional (3D) colored models.
Geometry acquisition and 3D imaging of objects, such as moving objects, is required in a wide variety of applications ranging from motion capture, such as marker-less motion capture, to 3D face recognition.
Various acquisition and reconstruction methods have been developed for this purpose. An example of a traditional acquisition technique is laser scanning, for example as described in F. Bernardini and H. E. Rushmeier, The 3d model acquisition pipeline. Comput. Graph. Forum, 2(21):149-172, 2002, which is incorporated herein by reference. This technique is currently implemented for modeling static scenes. Another technique, which allows faster acquisition, is described in U.S. Pat. No. 7,224,384, filed Sep. 8, 1999, that teaches an optical imaging system with a taking lens system that collects light from a scene being imaged with the optical imaging system, a 3D camera that comprises at least one photo surface that receives light from the taking lens system simultaneously from all points in the scene and provides data for generating a depth map of the scene responsive to the light, and an imaging camera with at least one photo surface that receives light from the taking lens system and provides a picture of the scene responsive to the light.
This method measures range data by calculating a depth profile of reflected photons resulting from an accurately gated and synchronized light pulse illuminating the scene. Time of light has low complexity reconstruction and can be implemented by a fast camera with linear response achieving video rates. The method involves compensating for the object albedo and other optical and manufacturing factors and therefore has a limited spatial resolution.
Another technique, which allows relatively fast acquisition, is a shape from stereo method that is based on multiple views. This method involves finding dense correspondences between two images of the same scene captured at two different viewing angles. Some of these methods use controlled source of illumination, which allows alleviating or completely resolving the correspondence problem. An example of the shape from stereo method is a structured light process where one or more known patterns, often grids or horizontal bars, is projected on a target space 99, a scene. The way that the one or more known patterns deform when striking surfaces in the target space 99 allows calculating the depth and surface information of the objects in the scene. An example for this technique is described in Patent Application NO. 2010/0079581 which describes imaging device capable of capturing depth information or surface profiles of objects is disclosed herein. The imaging device uses an enclosed flashing unit to project a projection sequence of structured light patterns onto an object and captures the light patterns reflected from the surfaces of the object by using an image sensor that is enclosed in the imaging device. The imaging device is capable of capturing an image of an object such that the captured image is comprised of one or more color components of a two-dimensional image of the object and a depth component that specifies the depth information of the object.
A recent review on coded light techniques can be found in C. Rocchini, P. Cignoni, C. Montani, P. Pingi, and R. Scopigno. A low cost 3D scanner based on structured light. In Eurographics 2001, volume 20, 2001 and a detailed description on pattern coding and reconstruction algorithms in A. M. Bronstein, M. M. Bronstein, E. Gordon, and R. Kimmel. High-resolution structured light range scanner with automatic Calibration, CIS-2003-06 technical report, Technion, 2006, both incorporated herein by reference.
Low-cost accurate depth acquisition based on coded light system is described in A M. B. Vieira, L. Velho, A. Sa, and P. Carvalho. A cameraprojector system for real-time 3D video. In DVPR '05, 2005, which is incorporated herein by reference. This document describes a scanning system which is based on coding part of the projected patterns in color. This approach requires a color camera and can be sensitive to the reflectance properties of the scanned objects.